Explain the Math of AC vs DC Charging

[theo1000]

Sorry, I need to correct you (and myself!)... the max rated current is 375A and the max PEAK current is 500A. The rated and max power are both 350kW. You can see the numbers in table 5 of the document linked below.

https://www.charin.global/media/pag...83-1619689951/charin_dc_ccs_power_classes.pdf

You maybe right though CharIN is the next standard to follow for upto 2MW for commercial vehicles and not in effect yet. CCS-1 is still the USA current standard.

I just know these things from the equipment side. Continuous 500 amp equipment allowing 500kw charging is under development right now, testing ongoing. So we will see 500kw Chargers under CCS-1. I would imagine CharINN will accommodate them.

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[EV Lab]

You maybe right though CharIN is the next standard to follow for upto 2MW for commercial vehicles and not in effect yet. CCS-1 is still the USA current standard.

I just know these things from the equipment side. Continuous 500 amp equipment allowing 500kw charging is under development right now, testing ongoing. So we will see 500kw Chargers under CCS-1. I would imagine CharINN will accommodate them.

Thank you!

I thought there were also some connector standards that limited the current to 350A... any higher requiring active cooling in the cable. Is that no longer the case?

I have only had experience with the BMS side of things, only getting involved with the plugs when trying to deal with vendors to get them.

 

[theo1000]

Active cooling necessary, as you can imagine @ 500 Amp continuous active plug cooling as well.

 

[dtbaker61]

While Darren Palmer hints it might be possible to do vehicle-to-home with the Mach E in the future,

the limiting factor on vehicle to home is access to the 12v current that can be extracted. This appears to be around 160amp at 12v nominal... so 2000 watts continuous would be the MAX continuous load the house can extract from MME.

 

[CHeil402]

the limiting factor on vehicle to home is access to the 12v current that can be extracted. This appears to be around 160amp at 12v nominal... so 2000 watts continuous would be the MAX continuous load the house can extract from MME.

I think they were referring to doing it similar to how the F150 appears that it will do it. To use an off-vehicle inverter connected to the DC CCS pins, so not through the 12 V battery and connected directly to the HVB, so capped at whatever the inverter can handle, likely >10 kW.

 

[dtbaker61]

I think they were referring to doing it similar to how the F150 appears that it will do it. To use an off-vehicle inverter connected to the DC CCS pins, so not through the 12 V battery and connected directly to the HVB, so capped at whatever the inverter can handle, likely >10 kW.

it is unlikely that a off-grid off-vehicle inverter will accept 350-450vDC from the traction pack. All available off-grid residential inverters are designed for 48vDC, or less. So Ford would have to ALSO release a high current dc-dc converter off-vehicle, which would get very expensive.

grid-tie solar inverters can accept high voltage DC, but they also need an existing 240vAC line voltage and frequency to sync to....

The only reasonable way to run an off-grid inverter is with 12,24,48 vDC
which means the wattage limit will be whatever the on-board dc-dc can put thru to the 12v connection points.

 

[CHeil402]

it is unlikely that a off-grid off-vehicle inverter will accept 350-450vDC from the traction pack. All available off-grid residential inverters are designed for 48vDC, or less. So Ford would have to ALSO release a high current dc-dc converter off-vehicle, which would get very expensive.

grid-tie solar inverters can accept high voltage DC, but they also need an existing 240vAC line voltage and frequency to sync to....

The only reasonable way to run an off-grid inverter is with 12,24,48 vDC
which means the wattage limit will be whatever the on-board dc-dc can put thru to the 12v connection points.

That would mean that you'd have to connect it to a 12 V terminal, which isn't easily accessible and not something the average consumer would do. The F150 (and CHAdeMO for that matter) do it through the EVSE connector which isn't tied to the 12 V DC side. So either you make the onboard EVSE AC inverter bi-directional and use the AC J1772 connector pins or you offload a DC/AC inverter and use the DC CCS pins (which is what the F150 appears to be doing, but we'll need to wait and see final implementation details).

Grid-tie solar only needs an external sync because its purpose is to connect to the grid and must be in sync with it to supply the grid with excess solar generation. This system can/would behave like a Tesla Powerwall which either acts as a grid-follower when connected to the grid or grid-forming if it's acting off-grid (which allows for a solar inverter to sync to it to recharge the battery as well).

 

[ChasingCoral]

it is unlikely that a off-grid off-vehicle inverter will accept 350-450vDC from the traction pack. All available off-grid residential inverters are designed for 48vDC, or less. So Ford would have to ALSO release a high current dc-dc converter off-vehicle, which would get very expensive.

grid-tie solar inverters can accept high voltage DC, but they also need an existing 240vAC line voltage and frequency to sync to....

The only reasonable way to run an off-grid inverter is with 12,24,48 vDC
which means the wattage limit will be whatever the on-board dc-dc can put thru to the 12v connection points.

Apparently the 80A Pro Charge Station uses the J-1772 connections for normal charging and the CCS DC connectors to feed electricity back to the grid. The Pro Charging Station acts as an inverter to take direct DC power from the HVB and feed 240V AC into the house.

 

[dtbaker61]

Apparently the 80A Pro Charge Station uses the J-1772 connections for normal charging and the CCS DC connectors to feed electricity back to the grid. The Pro Charging Station acts as an inverter to take direct DC power from the HVB and feed 240V AC into the house.

hhmmm well I'll be interested to hear more about that for sure.
backfeed of AC power has to sync to grid if grid is up, but has to supply it's own heartbeat if off-grid. All the off-grid inverters I am aware of require battery dcIN < 48v

 

[Racing_Andy]

hhmmm well I'll be interested to hear more about that for sure.
backfeed of AC power has to sync to grid if grid is up, but has to supply it's own heartbeat if off-grid. All the off-grid inverters I am aware of require battery dcIN < 48v

Ford's Darren Palmer talks about this in an Electrek podcast. It does sound like the car is delivering DC power via the CCS pins and the "Pro Charge Station" is acting as the inverter.
It sounds like this may be possible for the Mach-e as well at some point.

 

[dtbaker61]

Ford's Darren Palmer talks about this in an Electrek podcast. It does sound like the car is delivering DC power via the CCS pins and the "Pro Charge Station" is acting as the inverter.
It sounds like this may be possible for the Mach-e as well at some point.

I KNOW its possible....
Just a question of how much current the onboard dc-dc can supply at 12v. Best info I've dug up so far is 160amps, at 12v nominal which would enable 2000watt continuous load fed from the HV battery.

 

[Racing_Andy]

I KNOW its possible....
Just a question of how much current the onboard dc-dc can supply at 12v. Best info I've dug up so far is 160amps, at 12v nominal which would enable 2000watt continuous load fed from the HV battery.

Sorry, I was late to the party with that Darren Palmer clip, hadn't read the whole string.

What I still don't understand is why the CCS would supply 12v to the charging station. Is there no way for it to feed the 400v directly from the battery?
Certainly the Lightning is feeding a much higher voltage if it can supply 9.6 kw of power back to the house (obviously no way it's 800A at 12v).
What am I missing?

 

[mixduptransistor]

hhmmm well I'll be interested to hear more about that for sure.
backfeed of AC power has to sync to grid if grid is up, but has to supply it's own heartbeat if off-grid. All the off-grid inverters I am aware of require battery dcIN < 48v

It's not designed to feed back to the grid, it's designed to be a battery backup while the grid is down. The documentation released so far all says that a transfer switch of some type will be required to be installed in the home

Also, the Lightning has 9.6kW of power available to all of the various 120 and 240 volt outlets around the truck, which is the same amount of power quoted as available for the backup power. Not a stretch to imagine that it's using its onboard Pro Power inverter with some switching in side the truck to re-wire the DC pins on the CCS connector when it's in home backup mode

 

[dtbaker61]

It's not designed to feed back to the grid, it's designed to be a battery backup while the grid is down. The documentation released so far all says that a transfer switch of some type will be required to be installed in the home

absolutely you would need to isolate the home from the grid before using the Mach-e, Lightning, or any other generator to power up the home in emergency.

 

[dtbaker61]

Sorry, I was late to the party with that Darren Palmer clip, hadn't read the whole string.

What I still don't understand is why the CCS would supply 12v to the charging station. Is there no way for it to feed the 400v directly from the battery?

correct.
no way to get to HV connection, and no standalone inverter I am aware of that is set up to run using a battery pack above 48v nominal (by code)

Certainly the Lightning is feeding a much higher voltage if it can supply 9.6 kw of power back to the house (obviously no way it's 800A at 12v).
What am I missing?

My guess is that the Lightning will offer 48v connection point from the on board dc-dc in addition to 12v used by 'normal' cabin loads, AND the dc-dc inverter on board with have higher thruput perhaps with better cooling since they are designing to higher output.

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